ARLINGTON (CBSDFW.COM) — A 6-year-old boy is in “very poor condition” after his brother shot him in the head with a rifle Sunday, Arlington police said.

Around 4:30 p.m. Sept. 15, police responded to a shooting call at a home on Cloyne Drive, where they found the boy with a gunshot wound to the head.

Police said the victim’s brother found an unsecured .22 caliber rifle at the home, didn’t realize it was real and shot his brother in the head.

Adults and several children were reported to be at the home during the shooting. The homeowners also claimed they didn’t know the rifle was in the home, and didn’t purchase the weapon.

During further investigation, the victim’s teenaged brother claimed he bought the rifle used in the shooting.

The 6-year-old — whose identity has not been released — is currently at a local hospital in “grave condition,” police spokesman Christopher Cook said at a news conference.

This is an ongoing investigation.